Mancini: Villa game a must win

The defending champions are 12 points behind Premier League leaders Manchester United and will find themselves 15 points adrift of their neighbours if Sir Alex Ferguson's team defeat Norwich on Saturday.

With the form that United are in at the moment, Mancini accepts City can have no margin for error.

"Every game will be like this. If we don't win and they continue to win, always," he said. "We talked about this last week. When you are 12 points behind it is normal that if you lose or don't win and Manchester United win the next game it will be difficult."

Mancini, though, refuses to admit defeat in his bid to retain the title and takes heart from City's comeback last season, when United had an eight-point advantage with six games to go.

"It is impossible we can think the season is finished now," he said. "There are 11 games to play, 33 points [available]: everything is possible. Last time we won the title six games to go [we were] eight points [behind].

"It is our job to play all the games 100% and try to win always. We should do our best from now to the end and after we will see what happens."

And the City boss has warned his players that their recent 2-0 victory over Chelsea will be in vain if they do not defeat Paul Lambert's side to keep up the pressure on United.

"If we don't beat Aston Villa, it is like we didn't do anything against Chelsea," he said.

The Italian was happy with the performance against Rafa Benitez's team, though, adding: "We played a really good game and it was important for us to beat Chelsea."